Vacuum discharge tube



March 31, 1959 N. WARMOLTZ VACUUM DISCHARGE TUBE Original Filed NOV. 6, 1951 Tiiiiiiii.

m a 2, 9 A\H,\

2 1?. 5. INVENTOR.

Mcozus MRMOLTZ United States Patent O VACUUM DISCHARGE TUBE Nicolaas Warmoltz, Eindhoven, Netherlands, assigno'r, by

mesne assignments, to North American Philips Company, Inc., New York, N.Y., a corporation of Delaware Original application November 6, 1951, Serial No. 255,096, now Patent No. 2,686,888, dated August 17, 1954. Divided and this application February 4, 1954, Serial No. 408,154

Claims priority, application Netherlands December 4, 1950 7 Claims. (Cl. 313-259) This invention relates to a vacuum discharge tube having an anode and cathode arranged on either side of an insulator, and constitutes a division of my copending application, Serial No. 255,096, filed November 6, 1951, now Patent No. 2,686,888.

Discharge tubes of this type have been suggested but the invention is concerned with tubes in which a cold cathode is arranged close to the anode by means of a thin insulator.

According to the invention, in a high-vacuum discharge tube which comprises at least an anode and a cathode arranged on opposite sides of and in contact with an insulator, the cold cathode, which has a smaller length than the anode, is arranged in contact with the insulator in such manner that the border line cathode-insulatorvacuum has the anode facing it on the opposite side of the insulator. Border line cathode-insulated-vacuum is defined as the region at the terminus of a cold cathode mounted on an insulating member disposed in an evacuated envelope. This arrangement permits a rectifying effect to be obtained, since the field intensity on the border line cathode-insulator-vacuum is higher than that on the border line anode-insulator-vacuum. The anode preferably has a greater length than the insulator, so that the mutual conductance of the discharge tube is substantially reduced in the conductive direction.

The longer the border line cathode-insulator-vacuum, the more current the tube is capable of passing at a predetermined voltage. If there are on one side of the insulator several border lines cathode-insulator-vacuum between which the insulator is not interrupted, it is advisable to arrange at a small distance therefrom a supplementary electrode which may function as an auxiliary anode or as a control grid.

The invention will now be described more fully with reference to the accompanying drawing, in which:

Figs. 1 and 2 show an electric discharge tube according to the invention in its simplest form,

Fig. 3 shows a discharge tube provided with an auxiliary electrode,

Figs. 4 and 5 show two sectional views of a tube according to the invention having a low mutual conductance, and

Figs. 6, 7 and 8, respectively show alternative embodiments thereof.

Referring to Fig. 1, the tube comprises a glass bulb 1, an anode rod 2 several mms. thick which is coated with a glass layer 3 of thickness 0.15 mm. and a cathode formed by a metal layer 4. The tube shown in Fig. 2 is a similar to that of Fig. 1 except for the cathode which is constituted by a ring so that two circular border lines cathode-insulator-vacuum are formed.

In the tube shown in Fig. 3 several rings 4 are mounted on the insulator 3 and a cylindrical auxiliary electrode 5 Patented Mar. 31, 1959 I 3 the insulating layer and 6 a number of strips which are united by a ring and extend in the direction of the axis of the anode.

Fig. 5 is a lateral view of this electrode system.

In the tube of Fig. 6 the cathode is formed by a conductive helix 8 mounted on the insulator 3, the auxiliary anode being again designated 5.

In the tube of Fig. 7, the anode is constituted by a flat plate 9 coated with a glass layer 10 having mounted on it a number of parallel strips 11. The same arrangement is made both on the front and on the rear of the plate, and Fig. 8 is a cross-sectional view of this electrode system, 12 designating the auxiliary electrode.

While the invention has been described in connection with specific examples and applications thereof, other modifications of the invention will be readily apparent to those skilled in the art without departing from its spirit and scope as defined in the appended claims.

What is claimed is:

1. A high vacuum discharge tube comprising an evacuated envelope, a rod-like anode disposed within said envelope, a cylindrical-like insulating member surrounding and embracing only a portion of the outer surface of said rod-like anode, and at least one ring-shaped cold cathode surrounding and being mounted on only a portion of the outer surface of said insulating member, whereby at least one edge of said cathode defines with said insulating member a border line cathode-insulatorvacuum and at least one end of said insulating member extends beyond said border line cathode-insulator-vacuum, one end of said anode extending beyond said end of said insulating member, said anode and said end of said insulating member defining a border line anode-insulatorvacuum displaced from said border line cathode-insulatorvacuum.

2. A high vacuum discharge tube comprising an evacuated envelope, a rod-like anode disposed within said envelope and extending a given distance therewithin, a cylindrical insulating member having a length smaller than said given distance surrounding and embracing an intermediate portion of said anode, at least one ringshaped cold cathode having a length smaller than the length of said insulating member surrounding and being mounted on the outer surface of an approximately central portion of said insulating member whereby each edge of said cathode defines with said insulating member a border line cathode-insulator-vacuum and a portion of said insulating member extends beyond each said border line cathode-insulator-vacuum, said anode extending beyond each end of said insulator to define therewith at least two border lines anode-insulator-vacuum, and means connected to said cathode and anode and accessible from outside of said envelope for applying a potential between said cathode and anode.

3. A high vacuum discharge tube as claimed in claim 2 in which the cathode comprises a plurality of spaced interconnected ring-shaped segments mounted adjacent one another on said insulating member.

4. A high vacuum discharge tube as claimed in claim 2 in which the radii of said anode, said insulating member, and said cathode are infinite, and said cathode further comprises a plurality of straight conductive segments conductively joined together at one end.

5. A high vacuum discharge tube as claimed in claim 2 in which a cylindrical control electrode surrounds said cathode and is spaced and insulated therefrom to control the discharge between said borderline cathoderinsulatorvacuum and said anode.

6. A high vacuum discharge tube as claimed in claim 2 in which said cathode comprises a helical conductor directly mounted on said insulating member. 7. A highva'cuumdischargetube asclaimed in claim 1' in which-the: other end of said insulatin'g member extends beyond the other end of' said'rod-like anode and is closed thereover; and the other end of said cathode is closed around said other end of said insulating member.

References Cited in the fileofthis patent UNITED STATES PATENTS Lewis Nov. 24, 1931 Knowles Aug. 16, 1932 Marvin et' a1 Apr. 10, 1934 Schroter Apr. 17, 1934 Noel Sept. 23, 1947 Warmohz Aug. 17, 1954 Warmoltz JuneS', 1956 

